• Journal of Welding and Joining
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• v.29 no.6
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• pp.56-64
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• 2011

Friction stir spot welding between 5454 aluminum alloy sheets with the different thicknesses of 1.4 and 1.0 mm was performed. In the welding process, the tool for welding was rotated ranging from 500 to 2500, and plunged to the depth of 1.8 mm under a constant tool plunge speed of 100 mm/min. And then, the rotating tool was maintained at the plunge depth during the dwell time ranging from 0 to 7 sec. The pull-out speed of the rotating tool was 100 mm/min. The increase of tool rotation speed resulted in the change of the macrostructure of friction-stir-spot-welded zone, especially the geometry of welding interface. The results of the tensile shear test showed that the total displacement and toughness of the welds were increased with the increase of the tool rotation speed, although the maximum tensile shear load was decreased. However, the change in the dwell time at the plunge depth of the tool did not produce the remarkable variation in the macrostructure and mechanical properties of the welds. In all cases, the average hardness in friction-stir-spot-welded zone was higher than that of the base metal zone. By the friction stir spot welding technique, the welds with the excellent mechanical properties than the mechanically-clinched joints could be obtained.

• The Journal of Korean Association of Computer Education
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• v.23 no.3
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• pp.17-30
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• 2020

Although the importance of Artificial Intelligence(AI) education is increasing, research on the development of test tools has not been conducted in AI education research in Korea has not been conducted. Accordingly, there is a limit to designing AI curriculum and analyzing the effect of the educational program. So, in this study, Test tool was developed that to measure the attitude toward artificial intelligence of middle school students. For the development of test tools, the objectives, components, factors, and test tools were developed through the discussion of AI education experts. The test tool was finally developed by item analysis, exploratory factor analysis and confirmatory factor analysis. Finally, the criteria of the developed test tool were analyzed. Future research is needed to analyze the effects of educational programs and to analyze factors affecting attitudes toward artificial intelligence in middle school students using developed test tools.

• The Journal of the Korea Contents Association
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• v.20 no.10
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• pp.338-352
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• 2020

This study identified essential areas of student satisfaction by presenting questions concerning each educational area. The measurement tool of this study was developed based on a literature review, and its validity and reliability were verified through qualitative research and exploratory and confirmatory factor analysis. To measure student satisfaction in university, we developed a tool comprising seven areas: curriculum and instruction; student advising, educational environment, student support, campus life, university image, and administrative services. A total of 54 questions were prepared, and 7 factors were derived. Cronbach's alpha was 0.970 for all questions and ranged from 0.70 to 0.93 for each factor. The results of the confirmatory factor analysis were GFI 0.830, CFI 0.916, TLI 0.910, RMR 0.047, and RMSEA 0.047, which confirmed the suitability of the research model. Moreover, the convergent validity showed that the questions in this tool consistently described the component areas. Therefore, the research tools developed in this study were found to be suitable for measuring student satisfaction.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.41-48
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• 2007

Since the advent of object-oriented(OO) technology, research and development projects have fumed out that OO technology could importantly contribute in productivity and reusability improvement. There are various research areas related to OO technology And two of major research fields in this areas are concerned in issues for CASE tools and component-based technologies. This paper discusses a trial of applying component-based technology to a CASE tool. This paper proposes the design and implementation issues obtained while we have incrementally developed OODesigner, an OO CASE tool, with compound document support functionality based on COM/OLE technology. As OODesigner with OLE container/server functionality has interoperability with other application programs of Windows system, it can provide more powerful documentation environment than other CASE tools. OODesigner can be used not only to design UML diagrams. but also enables us to make more expressive documentation cooperatively with various kinds of OLE-enabled software like Recorder and Excel. Therefore powerful and consistent documentation activity can be achieved with the tool.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.1
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• pp.18-24
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• 2020

The KSLV-II project with high difficulties technically requires thorough technical management during long-term life cycle more than 10 years for launching into space. The TRL is a quantitative indicator developed by NASA widely used all over the world to measure technology maturity of a system development objectively and consistently. The TRL is also used to make sure technology level and to establish a future direction in the KSLV-II project. The TRL has advantage enable to identify a technology level through quantitative indicators. However, it takes a lot of efforts such as trials and errors, time and cost to apply it to the project considering the project environments, and stakeholder needs. These include not only to establish TRL management plan from ideal, conceptual and abstractive standards/guidelines such as NASA's, but also to construct TRL management environment enable to apply and manage harmoniously. In the KSLV-II project, it is required to figure out current technology level and technology development trend in the future, to access conveniently, to share related data in real time, and to update periodically for the comprehensive TRL management. From the reason above, the TRL management environment was built by using the systems engineering tool already has been used for other system management data such as requirements in the project. It also could be accomplished a practical management basis of systems engineering from the traceability among system management data including TRL. In this paper, case study results are introduced to manage the TRL for the space launch vehicle using the systems engineering tool in the KSLV-II project.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.324-330
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• 2013

This paper describes a novel method to surface large optics mirror with an extremely high hardness, which could replace the high cost of the repetitive off-line measurement steps and the large ultra-precision grinding machine with ultra-positioning control of 10 nm resolution. A lot of diamond pellet to be attached on the convex aluminum base consists of a grinding tool for the concave large mirror, and the tool was pressured down on the large mirror blank. The tool motion at an interval on the spiral path was controlled with each feed rate as the dwell time in the conventional computer-controlled polishing. The shape to be surfaced was measured directly by a touch probe on the machine without any separation of the mirror blank. Total 40 iterative steps of the surfacing and measurement could demonstrate the form error of RMS $7.8{\mu}m$, surface roughness of Ra $0.2{\mu}m$ for the mirror blank with diameter of 1 m and spherical radius of curvature of 5400 mm.

• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.285-294
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• 2018

An experimental study has been carried out to analyze the effect of cutting parameters (cutting speed, feed and depth of cut) and tool nose radius on the surface roughness and the cutting force components during hard turning of the AISI 52100 (50 HRC) steel with a ceramic cutting tool. The tests have been conducted according to the methodology of planning experiments, based on an orthogonal plan of Taguchi (L27). By using the response surface methodology (RSM), the components of the cutting force and the roughness of the machined surface were modeled and the effects of the input parameters were analyzed statistically by ANOVA and RSM. The results show that the feed (f), the tool nose radius (r), the cutting speed (Vc), the interaction between feed and tool nose radius ($f{\times}r$) as well as that of the quadratic effect ($f^2$) all have significant effects on the surface roughness (Ra). The feed is the most influencing factor with a contribution of 47.31%. The components of the cutting force were strongly influenced by the depth of cut, followed by the advance with a lower degree. By comparing the experimental values with those predicted by the models of the cutting force components and the surface roughness, it appears that they are in very good correlation.

• Proceedings of the Korea Society of Design Studies Conference
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• 2000.11a
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• pp.120-121
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• 2000

신상품 개발을 위한 트랜드 이미지의 수집과 분석(타운워칭, 캐털로그 분석 등)은 이미 디자인 전개과정에 깊숙히 자리잡고 있는 기법이다. 그러나 대부분의 경우 트랜드 이미지의 수집은 디자이너의 직관에 의존하는 경우가 많았기 때문에 실질적인 시장상황을 반영한다고 하기에는 다소 힘들었던 것이 사실이다. (중략)

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.4
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• pp.75-86
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• 1998

We address the problem of determining the optimal processing times and pallet/fixture allocation in Flexible Manufacturing systems in order to minimize tool cost while meeting throughput targets of multiple part types. The problem is formulated as a nonlinear program superimposed on a closed queueing network of the FMSs under consideration. A numerical example reveals the potential of our approach for significant cost saving. We argue that our model can be Integrated Into the process planning system of an FMS to generate efficient process plans quickly.

• Journal of Distribution Research
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• v.3 no.1
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• pp.31-54
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• 1998

The purpose of this research is three-fold; 1, establish the causal model of market-orientation, customer satisfaction, employee satisfaction and firm's perfor-mance. 2. testify the hypothesis derived by the model on a service industry of fastfood franchise. 3. develop the diagnostic tool for managing the service firm from the perspective of CS. The results show us; 1. customer satisfaction increases the performance of franchise store. 2. employee satisfaction does not necessarily increases customer satisfaction in a short-run, however the long-run impact of employee satisfaction on customer satisfaction is conjectured to be increased. 3. Satisfaction Portfolio Analysis can be utilized as management tool to improve the customer satisfaction and employee satisfaction for service industry.